Fibrous products with inorganic binders



Oct. 2, 1934. w. A. BoUGHToN 1,975,081

` FIBRoUs PRODUCTS WITH INORGANIC BINDERS Filed sept. 12, 19:52

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M/TY BE SHTl/FHTED WITH HDHESI/E.

MICH FLN/(E6 0079750 WITH DHE/VE.

Patented Oct. 2, 1934 FIBRoUs PRODUCTS WITH INORGANIC BINDERS Willis A. Boughton, Cambridge, Mass., assigner to New England Mica Co., Waltham, Mass., a corporation of Massachusetts Application September 12, 1932, Serial No. 632,849 15 Claims. (Cl. 154-26) This invention relates to fibrous inorganic binders, of the class which are temperature resistant, oil resistant, and electrically insulating, and the like, of various shapes, such sheets, rings, special objects, etc., from non-comafter baked under pressure.

products with hesive and flake mica, the assembled sheet there- In the preparation of temperature and elecas trical resisting and insulating materials of various kinds prepared `from fibrous products, it has bustible fibrous matter, such as asbestos, mineral heretofore been diiiicult to secure adequate rewool, slag wool, and other inorganic fibrous matter, and when desired such non-combustible matter may be associated gums as sistance to high temperatures because of the associated with mica; or frequent necessity of using .organic resins and binder, and these by nature decompose with combustible matter, such as cotton goods or at temperatures of 30G-600 F., thus limiting the 65 fibres, woolen goods or fibres, paper pulp, etc.,

temperatures at which the materials may be the raw material to be saturated or coated with used safely in the' manufacture of a large variety a highly viscous adhesive aqueous association oi products,

of an inorganic colloid, as described hereafter, I have discovered that the general or mixtures of such viscous aqueous colloidal asinorganic substances sociations, and the combined mass suitably hesive pressed, shaped, dried, heated, or otherwise successfully cmplOyed in the bonding, treated mechanically. The invention also contemplates the manufacture of such products from fibrous cellulose matter, or wool or the like, singly erties. or mixed with such brous matter as cotton, or cotton goods, paper pulp, Wool or woolen goods, or Without chemical modification is etc., associated with the highlyviscous adhesive aqueous colloidal association, or mixtures of sucli'"'patents, as follows: Mica products with colloidal associations.

An object of the invention is to provide a product which is fire resistant, oil resistant, possessing high electrical insulating properties, and which may be formed into a plurality of shapes.

A further object is to provide a product which may bel converted into washers, gaskets, packings, etc., which remain tight and do not decompose when subjected to temperatures up to about 600 F.

A further .object is to provide SI'. NO. 546,153.

Molded laminated mica products with 13, 1932, SI. No. 599,844.

group of that form highly viscous adcolloidal associations with Water may be stiffening This group of colloidal inorganic binders with fully described in my several pending applications for inorganic binders', filed March 9, 1931, Serial No. 521,378. 90 General processes of bonding, led June 22, 1931,

Methods of restraining crystallization,"filed June 22, 1931, Sr. No.

546,154. inorganic binders and methods of making the same (W. A. Boughton and W. R. Mansfield), filed March The substances used as binders include such compounds as sodium metapho'sphate, NaPOa; a product which sodium monoborate, NaBO2; other alkali meta- 90- inat least one stage of manufacture is reversibly phosphates and monoborates such as the respecas that of asphalt, or practically solid ing on the amount of water in colloida tive ammonium, lithium, and potassium compounds; also a few other chemically related compounds; also a variety of salts of the element beryllium; also, mixtures of these substances may be used. They are all characterized by the property of forming highly viscous adhesive aqueous co1- loidal associations, the viscosity usually being greater than that of glycerine and often as great dependl association with the salt molecule. lThese substances hold tenacously to their colloidally attached water, as described below, yielding it up only slowly at temperatures considerably above the -normal of brous product in accordance with this inboum g po1nt of a concentrated aqueous salt so- Ventwm Showmg a' lammated Sheet Conlstmg 0f lution. Definite analyses are difficult to obtain layers of asbestos or other fibrous maternal which because of the abnormal physical nature of Such re is still f them at maybe impregnated With adhsive aS described substances, but I have foundv that the herein, and intermediate alternate layers of adresidual water associated with several o als temperatures upwards of 300 and in certain instances upwards of 450 F. The differences in viscosities between various concentrations of such compounds is striking. With sodium metaphosphate, for example, the 15 percent solution is less viscous than glycerine, while the 60 percent solution is as viscous as a heavy, slow-flowing tar. Solutions of ammonium metaphosphate or metaphosphoric acid may be prepared which are so viscous as to be essentially solid at ordinary temperatures.` In general, the smaller amount of water associated with such an anomalous inorganic substance, the higher its viscosity at ordinary temperatures.

Sodium metaphosphate is known to exist in several polymeric forms. To develop in it the bonding property utilized Vin this invention I form an aqueous solution of the glassy hexapolymer at a temperature below the boiling point of water and as rapidly as possible, The common commercial powdered sodium metaphosphate is usually a mono-, di, or tri-polymer, and cannot be so used until after fusion when it is transformed to the glassy hexa salt. Similarly, crystalline sodium monoborate is an aqueous association, but a non-useful form in the sense of this invention. An aqueous solution if dilute shows no unusual viscosity and if concentrated crystallizes on cooling and standing, again being useless for this invention. Only when of a correct intermediate concentration, about percent to about 40 percent, or higher, and heated under pressure does -it become a bonding material of desirable properties. The bonding property is therefore not necessarily an inherent property but one that may be developed as the result of treatment or of careful control of conditions.

The fibrous matter may rst be impregated with a plastic in liquid form, such as a solution of a lacquer, then sprinkled with the aqueous inorganic colloid body, or it may be drawn through a vat containing the said aqueous inorganic colloid body, and the resulting pulp squeezed, suitably shaped and dried, or the preliminary impregnation may be omitted. The salt content in the dried vproduct will vary with the intended use of the (A) Fbrous mineral products and inorganic binder The fibrous mineral products used may include.

asbestos in any o1 its several forms and prefer-` ably made up into sheet form. Also, such products as mineral wool, slag wool, etc. Thus commercial asbestos paper and asbestos cloth are very suitable materials. But in the following specification, wherever asbestos paper is specifically referred to, it must be understood that any other mineral fibre may also be employed with similar results.

When the inorganic binders referred to above are employed with micaceous and similar materials as described in my earlier patent applications, no observable reaction takes place between the mica and the binder. The latter under controllable conditions functions as an increasingly viscous adhesive body, losing its associated water slowly, and yielding a product that may be molded at some deiinite elevated temperature depending on thertemperature of the prior heating and the resulting residual colloidal water content.

With asbestos, however, these colloidal inorganic binders act diierently. Upon saturation of thev asbestos with the binder there is the expected easy absorption; and the product is then soft, flexible and capable of being shaped. But when the resulting mass or sheet is dried and heated somewhat above 220 F. it becomes inflexible, hard and semi-crystalline, due (it appears) to a chemical reaction between the binder and the complex silicate of the asbestos. Such a product in sheet form is highly useful in the manufacture of washers to withstand elevated temperatures, for the preparation of stiff, nonsoftening, high temperature resisting and insulating forms or special shapes, for the preparation of such forms and shapes that shall be oil resisting to a high degree, and for many other products which acquire many unique and valuable properties.

Moreover, when for example asbestos paper is saturated with an inorganic binder such as a viscous colloidal solution of sodium metaphosphate, and before being dried and heated is adhesively combined with a layer of integrated mica sheet prepared with inorganic binder as previously described (general process of bonding application) and the combination thenpressed and heated either flat or in a mold, permanently formed products such as sheet insulation, commutator rings, and various shapes and forms may be prepared that are useful in industry and an improvement over similar products made with organic binders, because of superior temperature resistance and strength at the higher temperatures.

(B) Fbrons vegetable products and inorganic binders Inorganic binding fluids of the class described above may also be used with vegetable fibrous materials yielding a new group of valuable products having, however, the temperature limitations in use imposed by the presence of organic material. However, in the lower ranges of temperature the binder functions as a reversible thermoplastic, as `described above. Thus with a sheet of cellulose fibre such as paper pulp laid loosely enough to be absorbent the binder is absorbed, and the sheet may then be dried and baked -best under pressures of about 200 pounds per square inch at any temperature up to about 400 F.

Below the drying temperature the sheet is stift' and hard; but a few degrees above that temperature it is flexible and may be shaped, resuming its hardness when cooled. Among the articles for which such products may be used areshoe stiffeners, clothing forms, low temperature heat and temperature resisting articles such as gaskets and the like, oil resistant members of various sorts, etc. Many otherf'application's will be obvious to those yfamiliar-with the eld of stiiened thermoplastic brous bodies.

1. A bondedproduct containing brous material bondedgwith an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwardsof 220 F., but below temperatures which will eliminate all water. f

2. A bonded product containing inorganic `material and organic material, bonded with an aqueous colloidal association containing atleast one adhesive selected from the group consisting of viscous colloidal aqueous associations or metaphosphoric acid radical compounds, monoborates,

and beryllium compounds, the dried product containing from about fteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water.

3. A bonded product containing asbestos, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monobrates, and beryllium compounds, the dried product containing from about iifteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F.,but below temperatures which will eliminate all water.

4. A bonded product containing organic fibrous material, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fifteen percent to upwards ofiorty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water.

5. A bonded product containing cellulose fibrous matter, bonded with an aqueous colloidal associa.-

from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fifteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water.

Y 6. A molded product consisting of a shaped mass containing brous material, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fifteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water. 7. A molded product consisting of a shaped mass of fibrous asbestos material, bonded with an aqueous colloidal association containing at least onel adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates,'and beryllium compounds, the dried product containing from about fteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water.

8. Sheet material containing fibrous asbestos material, bondedwith an aqueous colloidal association containing at least one adhesive selected from the group consistingof viscous colloidal -aqueous associations of metaphosphoric acid associated with cellulose fibrous matter, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fifteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but belouT temperatures which will eliminate all water. l

l0. Insulating material for commutators vco sisting of laminated mica and asbestos bre, bonded with an aqueous colloidal association containing at least one adhesive selected vfrom the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical com` pounds, monoborates, and beryllium compounds,

the dried product containing from aboutv fifteen percent to upwardsA of forty percent of the compound, and bonded under pressure aty temperatures upwards of 220 F., but below temperatures which will eliminate all water.

l1. Composite insulating products consisting of sandwiched layers of mica andV asbestos `fibre, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium` compounds,

the dried product containing from about fteen tion containing at least one adhesive selected percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures v which will eliminate all water.

12. Compite insulating products consisting of associated mica flakes and asbestos libre, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fteen percent to upwards of forty percent of the compound, and bonded underfpressure at temperatures upwards of 220 F., but below temperatures which will` eliminate all water.

13. Composite packing, consisting of a mass of associated mica akes and asbestos fibre, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal aqueous associations of metaphosphoric acid radical compounds, monoborates, and beryllium compounds, the dried product containing from about fifteen percent to upwards of forty percent of the compound, and bonded under pressure at temperatures upwards of 220 F., but below temperatures which will eliminate all water.

14. A bonded product containing brous material, said material first impregnated with an organic liquid plastic, and thereafter bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting o! viscous colloidal aqueous associations of metaphosphoric acid radical compounds. monoborates.' and beryllium compounds, the dried product containing iromabout fifteen percent to about thirty percent of the compound, and bonded under 5 pressure at a. temperature of about 250 F., but below temperatures which will eliminate all water.

l5. A bonded product containing vegetable ilbrous material, bonded with an aqueous colloidal association containing at least one adhesive selected from the group consisting of viscous colloidal CERTIFICATE aqueous associations o! metaphosphoric acid radical compounds, monobor'ates, and beryllium compounds, the dried product containing from about fifteen percent to upwards oi' torty percent of the compound, and bonded under pressures oi about 200 pounds per square inch, and at a temperature not above 400 F., but below temperatures which will eliminate all water.

WILLIS A. BOUGHTON.

October 2, 1934.

certified that errorappears in the printed specification of the Page 3,`line 82, claim that vthel saidLetters therein that the same may conform Leslie FrazerI Acting Commissionerof Patents.

u OF CORRECTION.

mentito. 1,975,081.

'Y WILLIS A. BOUGHTON.

It is hereby above numbered patent requiring correction as follows: 8, after "bonded" insert the words under pressure; and Patent should be read with this correction to the record of the case in the Patent' Office. Signed and sealed this 30th day of October, A. D. 1934.

.ss (Seal) ian 4 p y metaphosphoric acid radical compounds. monoborates.' and beryllium compounds, the dried product containing iromabout fifteen percent to about thirty percent of the compound, and bonded under 5 pressure at a temperature of about 250 F., but below temperatures which will eliminate all water. 15. A bonded product containing vegetable brous material, bonded with an aqueous colloidal association containing at least one adhesive selectl0 ed from the group consisting of viscous colloidal aqueous associations o! metaphosphoric acid radical compounds, monobor'ates, and beryllium compounds, the dried product containing from about fifteen percent to upwards oi' torty percent of the compound, and bonded under pressures ol about 200 pounds per square inch, and at a temperature not above 400 F., but below temperatures which will eliminate all water.

WILLIS A. BOUGHTON.

CERTIFICATE OF CORRECTION.

Patent No. 1,975,081. October 2, 1934.

'Y n n WILLIS A. BOUCHTON.

I It is hereby certified that errorappears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 82, claim 8, after "bonded" insert the words under pressure; and that .thel saidLetters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent' Office. l

3 Signed and sealed this 30th day ol October, A. D. 1934.

p Leslie FrazerI .sa (Seal) Acting Commissionerof Patents.

oc nn` 

